From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark McLoughlin Subject: [PATCH 3/4] KVM: gracefully handle zero in kvm_free_irq_source_id() Date: Fri, 28 Nov 2008 10:26:10 +0000 Message-ID: <1227867971-1716-3-git-send-email-markmc@redhat.com> References: <1227867951.3643.24.camel@blaa> <1227867971-1716-1-git-send-email-markmc@redhat.com> <1227867971-1716-2-git-send-email-markmc@redhat.com> Cc: kvm@vger.kernel.org, Sheng Yang , Mark McLoughlin To: Avi Kivity Return-path: Received: from mail03.svc.cra.dublin.eircom.net ([159.134.118.19]:36811 "HELO mail03.svc.cra.dublin.eircom.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751446AbYK1K13 (ORCPT ); Fri, 28 Nov 2008 05:27:29 -0500 In-Reply-To: <1227867971-1716-2-git-send-email-markmc@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Allow kvm_free_irq_source_id() to be called with a zero ID. Zero is reserved for KVM_USERSPACE_IRQ_SOURCE_ID, so we can guarantee that kvm_request_irq_source_id() will never return zero and use zero to indicate "no source ID allocated". Signed-off-by: Mark McLoughlin --- virt/kvm/irq_comm.c | 14 ++++++++++---- 1 files changed, 10 insertions(+), 4 deletions(-) diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c index db75045..869f5e8 100644 --- a/virt/kvm/irq_comm.c +++ b/virt/kvm/irq_comm.c @@ -72,11 +72,15 @@ int kvm_request_irq_source_id(struct kvm *kvm) unsigned long *bitmap = &kvm->arch.irq_sources_bitmap; int irq_source_id = find_first_zero_bit(bitmap, sizeof(kvm->arch.irq_sources_bitmap)); + if (irq_source_id >= sizeof(kvm->arch.irq_sources_bitmap)) { printk(KERN_WARNING "kvm: exhaust allocatable IRQ sources!\n"); - irq_source_id = -EFAULT; - } else - set_bit(irq_source_id, bitmap); + return -EFAULT; + } + + ASSERT(irq_source_id != 0); /* KVM_USERSPACE_IRQ_SOURCE_ID reserved */ + set_bit(irq_source_id, bitmap); + return irq_source_id; } @@ -84,7 +88,9 @@ void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id) { int i; - if (irq_source_id <= 0 || + if (!irq_source_id) + return; + if (irq_source_id < 0 || irq_source_id >= sizeof(kvm->arch.irq_sources_bitmap)) { printk(KERN_ERR "kvm: IRQ source ID out of range!\n"); return; -- 1.5.4.3